2009/5/8 Kristian Høgsberg <k...@bitplanet.net>: > From: Kristian Høgsberg <k...@redhat.com> > > This patch adds a vblank synced pageflip ioctl for to the modesetting > family of ioctls. The ioctl takes a crtc and an fb and schedules a > pageflip to the new fb at the next coming vertical blank event. This > feature lets userspace implement tear-free updating of the screen contents > with hw-guaranteed low latency page flipping. > > The ioctl is asynchronous in that it returns immediately and then later > notifies the client by making an event available for reading on the drm fd. > This lets applications add the drm fd to their main loop and handle other > tasks while waiting for the flip to happen. The event includes the time > of the flip, the frame counter and a 64 bit opaque token provided by > user space in the ioctl.
Great idea with the poll/read stuff. I think you have the userspace <-> kernel part pretty much all figured out now. [SNIP] > + > +/** > + * drm_mode_page_flip - page flip ioctl > + * @dev: DRM device > + * @data: ioctl args > + * @file_priv: file private data > + * > + * The page flip ioctl replaces the current front buffer with a new one, > + * using the CRTC's mode_set_base function, which should just update > + * the front buffer base pointer. It's up to mode_set_base to make > + * sure the update doesn't result in tearing (on some hardware the base > + * register is double buffered, so this is easy). > + * > + * Note that this covers just the simple case of flipping the front > + * buffer immediately. Interval handling and interlaced modes have to > + * be handled by userspace, or with new ioctls. > + */ > +int drm_mode_page_flip(struct drm_device *dev, void *data, > + struct drm_file *file_priv) This function should have _ioctl appended to it. It should also go into the drm_crtc.c file. And should not use drm_crtc_helper functions and structs since those are not apart of the core kms implementation. Also I rather see as much as possible of the code below be put in the generic part and not just wrap this functions in a small function. [SNIP] > + /* > + * The mode_set_base call will change the domain on the new > + * fb, which will force the rendering to finish and block the > + * ioctl. We need to do this last part from a work queue, to > + * avoid blocking userspace here. > + */ > + crtc->fb = obj_to_fb(fb_obj); > + ret = crtc_funcs->mode_set_base(crtc, 0, 0, NULL); We should not block on rendering in the ioctl but do the call from a worker thread. And you probably need one thread per crtc. Also holding the struct_mutex while waiting for rendering might blow up in your face big time if the rendering command takes a long while to complete. [SNIP] > + > + /* > + * Unpin the old fb after setting a mode. Must be called > + * after the old framebuffer is no longer visible, ie, after > + * the next vblank, typically. > + */ > + void (*mode_unpin_fb)(struct drm_crtc *crtc, struct drm_framebuffer > *fb); I was going to say that should probably go on the framebuffer functions but the framebuffer doesn't have any helper functions. Cheers Jakob. ------------------------------------------------------------------------------ The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
